Subjects will receive bilateral (both sides) breast and axillary PEM scans. All recruited subjects chosen for the study will have biopsy proven breast cancer and are eligible for chemotherapy. They will undergo bilateral breast MRI for staging which is considered standard of care. Breast MRI and PEM scans will be performed at at baseline (phase 0 or pre-operative phase), 2nd MRI and PEM after 1 to 2 weeks of NAC (phase 1) and 3rd MRI and PEM after 1 to 2 weeks of phase 1 (phase 2). DCE-MRI and PEM will be performed not more than 14 days apart within each phase. Cranio-Caudal (CC) and Medial Lateral Oblique (MLO) PEM views will be performed of both the ipsilateral and contralateral breast and axillae by a Mammography Technologist trained in mammographic positioning.